The purpose of the invention relates to a new fluid temperature blending control system which assists in attainment of a desired fluid discharge temperature by means of an improved fluid temperature mixing indicator and an apparatus of fluid control valves. The invention further implies relevant advancements in blending control though lower manufacturing costs, a reduced number of components, greater ease of operation, and a higher reliability during use. More particularly the invention incorporates efficient developments in the means of activating the indicator system, method and presentation of fluid control valve handle adjustment directions, and in manual selection of fluid temperature ranges for which achievement or need for further control valve handle manipulation is communicated to the operator.
Much exists of prior art in fluid temperature mixing indicators, these devices are well known in both industrial and domestic applications for providing consistent temperature blending of a plurality of fluids that are emitted from common devices such as; lavatory faucets, bath and shower installations, and photographic development processing equipment. The majority of said devices consists of simple mechanical elements which produce indicating results by display of analog readings from mercury of bi-metalic sensors. U.S. Pat. Nos. 2,171,992 and 3,960,016 are typical of these early devices and are representative of a general means of mechanical sensor detection and display indication. Such mechanical devices have been notably unsatisfactory because they contain indicator scales which are often difficult to interpert, respond slowly to changes in the fluid media temperature, and are not easily calibrated. Although these mechanical types of mixing indicators have been marketed for sometime their popularity with the public has received limited acceptance for they continue to be utilized for lack of low cost commercially available alternatives.
Modern temperature indicators and automatic control mixing valves exampled in U.S. Pat. Nos. 3,721,386 and 3,927,571 have taken advantage of technology improvements of recent years in electronic temperature sensing and control to produce devices in related disciplines which represent a simplified and more responsive indicator means with techniques that are now standard to the art. These devices typically employ two or more signal indicating means which translate and display electrical resistive changes of temperature sensor elements in the fluid discharge path, as exampled in Brick et al, and whose output can be further amplified into electromechanical means to adjust and regulate a fluid blend automatically. Although said patents are representative of a large embodiment of such devices that contain electronic temperature sensing and display, none possess means for communicating precise indications needed for specific control or adjustment, or are activated as a result of fluid flow, or allow for a broad range of application in public use.
My U.S. Pat. No. 4,241,868 discloses an apparatus which overcomes many of the aforementioned difficulties by providing a fluid temperature mixing indicator consisting of; a plumbing fixture device which utilizes fluid valves having control handles to control and combine a plurality of fluids of different temperatures, an encompassing valve body to include fluid inlets, a mixing chamber with an outlet for emitting a fluid discharge, and an indicating signal means acting as an integral part to display the fluid discharge temperature. The described indicating signal means further provides and communicates need for particular manual control handle adjustment to achieve a predetermined temperature range of the blended fluid discharge. Additionally, the described device offers indicator activation upon fluid flow, automatic emergency shutdown temperature regulation through an in line electromechanical valve means, and electronically translated temperature indications which are readable under varying lighting conditions.
While the method and apparatus described in said prior art application and cited in patents are of considerable value in indication and control of fluid temperature blending, the usefulness of such devices would be greatly increased if they could be easily manufactured, obtain a higher reliability of activation under varying fluid pressure conditions, allow an array of alternative indicating means for persons with vision impairments, and permit selection of responsive temperature thresholds to suit a variety of operators. This prior art has been deficient in providing suitable long-term operation especially with fluids that contain heavy concentrations of alkalis or acids which corrode actuating mechanisms, where heavy parts per million pollution ratios in the discharge render sensor elements ineffective, and when high gas to liquid ratios exist causing erroneous readings.
Among several objects of the prior art form it may be further noted that sequencing of display indicator elements which depict the need for control adjustment or its attainment permitted possible confusion of the operator in that achievement of a desired temperature range was related by all signal display indicators being illuminated or activated. Experience has shown that proper sequencing avoids this problem by allowing all signal display indicator elements to remain in a deactivated condition when the correct fluid discharge temperature blend ratio was obtained thus clearly denoting achievement of the correct temperature range.